小兴安岭红松阔叶混交林林隙土壤温度的时空分布格局

Spatiotemporal distribution pattern of soil temperature in forest gap of Pinus koraiensis-dominated broadleaved mixed forest in Xiao Xing'an Mountains

采用网格法和十字样线法布设样点,在各样点安置地面温度表和曲管地温表,于2006年5—9月,测定了小兴安岭红松阔叶混交林林隙地表温度、地表最低和最高温度以及浅层(5、10、15和20cm)土壤温度,分析了该区林隙土壤温度的时空分布格局.结果表明:研究区林隙地表温度的高值区均未出现在林隙中心,其出现位置具有明显的日变化规律,出现次序依次为林隙的西北侧、北侧和东侧;在地表温度的高值区域内,最高温度由高到低的时间排序为14:00、12:00、10:00和16:00,其他时间林隙地表温度的分布较均匀;不同月份研究区林隙地表温度空间分布的复杂程度及斑块等级有所不同;各月林隙地表温度的高值区均位于林隙西北侧和东侧,呈不对称分布;树木生长季初期(5月)和末期(9月),研究区林隙地表温度平均日较差较大,而树木生长旺季(6—8月)却相对较小;东西方向上各观测点5、10、15和20cm土壤温度呈双峰型日变化规律,南北方向上呈不明显的单峰型日变化趋势;各月在东西方向上的土壤温度呈双峰型变化趋势,南北方向上除5月呈随机变化以外,其余月份均呈单峰型变化趋势.

By using grid and transect methods, measurement plots were established in forest gap of Pinus koraiensis-dominated broadleaved mixed forest in Xiao Xing＇ an Mountains, and soil surface thermometer and bended-tube thermometer were placed at each plot. The soil surface temperature, its maximum and minimum temperature, and the temperature at 5, 10, 15, and 20 cm soil depths were measured from May to September in 2006, aimed to investigate the spatiotemporal distribution pattern of soil temperature in the forest gap in study area. The high-value region of soil surface temperature in forest gap was not at gap center, but had an apparent diurnal variation, with the sequence of northwestern, northern, and eastern sides of the gap. Within this high-value region, the maximum temperature from high to low was in the time order of 14：00, 12：00, 10：00 and 16：00. At any other time, the soil surface temperature in forest gap distributed evenly, with no high-value region appeared. The complexity degree and patch grades of spatial distribution of soil surface tem- perature were different in months, and their high-value regions were at the north-western and eastern sides of the gap, with an asymmetric distribution. The mean diurnal range of soil surface temperature was bigger in the tree＇ s early and late growth periods （ May and September）, but relatively smaller in fast growth period. As for the mean daily and monthly soil temperature at 5, 10, 15, and 20 cm depths, a bimodal behavior was observed in east-west direction. The mean daily temperature in north-south direction exhibited an unapparent single peak behavior, and the mean monthly temperature except in May presented a single peak variation pattern.